The objectives of this project are to obtain descriptive data on father-infant interaction in natural settings and to analyze the father's influence on the infant's social, cognitive and motivational development. With a sample of firstborn 5-month-old infants, assessments include observations of father-infant, mother-infant and husband-wife interaction, a Q-sort technique to measure parental perceptions of infant temperament, parental interviews, and the Bayley Scales of Infant Development. A major goal is to develop a conceptual model for understanding the distinctive experiences provided by the father within the nuclear family.